This invention relates to a device for instantaneously generating steam; in particular, to a steam generating device adaptable to be associated with a compact device such as a hair dryer of handhold type which supplies hot air for arrangement of hair.
For example, when a person arranges his dry hair with a hair dryer of handhold type, it is desirable to provide moisture to the hair by blowing steam against the hair before arranging his hair with the hair dryer. Therefore, it is desirable that the hair dryer be provided with a device for generating steam. Such device must be safe and compact and be able to instantaneously generate steam.
There is a well known device for generating steam such as in an electric steam iron. This device is of boiler type in which water is received in a container and heated to boiling by a heater so as to produce steam. Thus, in use, such device can not be inclined beyond a certain angle; otherwise, there is a danger that hot water will flow out from the container through the outlet for steam. Further in such device should the container be small there is a danger that boiling water will escape off through the outlet for steam regardless of the inclination of the device. Further, the device can not instantaneously generate steam and is required to have a large heater to heat the water. Thus, the boiler type device is not suitable for a compact device such as a hair dryer of handhold type.
There is another well known device for generating steam in which drops of water are intermittently supplied on a metallic vessel which is preheated and each drop is evaporated to generate steam. This device has the advantages that the device can be made in small size and it does not require a large size heater and can generate steam in a short time in comparison with the boiler type device described hereinbefore. However, with the evaporation of each drop of water there is considerable heat loss, so that the temperature of the surface of the vessel drops, and it becomes necessary to heat the surface a short time after each evaporation in order to insure continuous evaporation of the drops of water intermittently supplied on the surface. To accomplish the above, it is required to provide a potential (or inner) heat in the evaporation vessel to enable it to supply heat to the surface in a short time. It was found that when, for example, the average drop of water per evaporation is 0.5 cc, the vessel should have potential heat such that the temperature of the surface thereof becomes about 145.degree. C to 160.degree. C. However, when the surface is heated to such a temperature, the drop of water supplied on the surface is dispersed by the heat of the surface and each dispersed water is sphered, i.e., the so called heat shock phenomenon occurs, so that it becomes impossible to evaporate all of the water in a short time. Thus, the steam pressure becomes low so that the field of application thereof is limited; for example, it is not suitable to use it for providing moisture to hair by blowing steam against hair before arranging hair by means of a hair dryer.